Firefighters training for underground explosions

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A scourge of underground explosions in electrical vaults has the Fire Department training its workers to deal with subterranean blasts.

A handful of explosions and fires in underground vaults operated by Pacific Gas and Electric, which is the power supplier for San Francisco, has the utility teaming up with the Fire Department to train firefighters in safely putting out the blazes. That partnership includes PG&E purchasing a new truck for the department that is specially designed to fight the vault fires.

In the last few months, firefighters have been taking tests online to prepare for an underground explosion, with lessons ranging from electrical safety to responding to a substation emergency, SFFD Deputy Chief of Operations Pat Gardner said.

The Fire Department uses carbon dioxide to put out fires underground, where a cauldron of chemicals and electric wiring would only get worse if doused with water. Their aging 3-ton truck designed for the task is being replaced by an even larger truck, paid for entirely by PG&E.

Power company spokesman Joe Molica said PG&E has always worked closely with the Fire Department, but as the company works on making its underground vaults safer, a new training protocol is necessary.

"We proactively work with our city partners to make sure we’re prepared for an emergency," Molica said.

Underground explosions and fires in The City have occurred at least seven times in the last year, with one blast knocking out power for days in a neighborhood.

The latest occurrence was an electrical problem in a vault at Geneva Avenue and Bayshore Boulevard on Monday. That blast knocked out power to 6,300 customers. A week earlier, a PG&E cable failure caused a boom and smoke to billow from a manhole at Battery and Pine streets at 6:30 a.m.

On July 27, power was cut to San Francisco’s City Hall after wisps of smoke were seen curling out of manhole covers in front of the stately building.

On July 6, a morning explosion under a manhole near the Ross clothing store on Fourth and Market streets due to a failed network connector caused the store to lose power, PG&E said. No one was injured but a handful of Muni buses had to be rerouted.

A fireball erupted from a manhole at O’Farrell and Polk streets June 12, knocking out power to 8,600 PG&E customers. Four blocks were closed for days and a shelter-in-place order was issued due to toxic smoke.